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Life on Earth. Chapter 10. Origins. Early Earth Oldest rocks suggest Earth is 4.5 billion yrs old Condensed gases and dust Very hot initially, but outer surface cooled Heat is still produced by inner core of Earth Location just right from Sun – liquid water

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Life on Earth

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Origins • Early Earth • Oldest rocks suggest Earth is 4.5 billion yrs old • Condensed gases and dust • Very hot initially, but outer surface cooled • Heat is still produced by inner core of Earth • Location just right from Sun – liquid water • Large oceans formed, atmosphere from volcanic activity • Oxygen was not present in the atmosphere

Origins con’t • Volcanic activity would have triggered large thunderstorms with lightening • Atmosphere would have had water vapor, methane gas, carbon dioxide nitrogen, hydrogen, hydrogen sulfide and ammonia. • From this mix arose organic molecules and the building blocks of nucleic acids and proteins

First cells • Replicating molecules – simple molecules that could make more copies of themselves, would have become more common. Probably RNA. • RNA can function like a protein enzyme, so alone RNA molecules might have been able to self replicate • Sealed self from external environment in a membrane

Cell membrane • If place phospholipids in salt solution, they will form spheres spontaneously • Such microspheres will even create new microspheres – but not replication as such • A combination of RNA or DNA with microsphere would give all of the components needed to call it life.

Mesozoic Era con’t • Largest dinosaurs dominated during the Jurassic Period (200-140 mya) • 2 large land masses formed • Mesozoic ended with impact of a large asteroid that cooled Earth rapidly • Mass extinction of most dinosaurs, others

The classic experiments performed in the 1950s by Harold Urey and Stanley Miller were the first to show that: A) simple organic molecules, such as amino acids, could form spontaneously in the laboratory under chemical conditions mimicking those of primitive earth.B) water (H2O) could be separated into atmospheric oxygen and H2 gas.C) cosmic microwave background radiation (CMB), a type of electromagnetic radiation, fills the entire universe and provides support for the “big bang” model of the origin of the universe.D) naturally occurring antibiotics, such as penicillin, could be used to treat bacterial diseases.E) the average bill size of a population of Darwin’s finches changed with environmental conditions, proving that microevolution can occur within a human lifetime.

Phase 1 of the creation of life on earth was _____________________. Phase 2 was the formation of self-replicating, information-containing molecules. Phase 3 was the development of a membrane, which enabled metabolism and created the first cells. A) the formation of small molecules containing carbon and hydrogenB) the formation of DNAC) the development of a nucleus, which enabled metabolism and created the first cellsD) the increase in the amount of atmospheric oxygenE) the formation of RNA

What is a species? • Different kinds of organisms • Populations that interbreed • Can’t breed with other organisms under natural conditions • Reproductively isolated

How do new species evolve? • Process is called speciation • Requires populations to become reproductively isolated • Populations evolve separately • Both change to the point that when they re-encounter each other, individuals from the two populations can no longer interbreed

Forms of Speciation • Allopatric speciation • A population is split • Migration of small group to an island • River changes course • Mountain building • Sympatric speciation • No physical barrier • Something else causes reproductive isolation

Horses and donkeys can breed and produce sterile offspring known as mules. Horses and donkeys remain separate species because of this hybrid sterility, which is: A) an allopatric barrier to reproduction.B) a postzygotic barrier to reproduction.C) a sympatric barrier to reproduction.D) a prezygotic barrier to reproduction.E) a good thing.

Tree of Life • Evolutionary history can be visualized as a tree with branches • Branches show relationships among different species and where speciation occurred • Phylogeny is the study of the evolutionary history of groups of species • Based on structures, development, behavior, and genetics

Convergent Evolution These are Analogous traits – similar but do not share an evolutionary history Homologous traits = jaw of bat and mouse = share an evolutionary history Structures of wings are very different Vertebrate eye and eye of octopus and squid share many characteristics, but = convergent evolution

Which of the following BEST explains the finding that the nuclear DNA of house cats and African wild cats has a very high degree of similarity? A) Convergent morphological evolution has occurred.B) Convergent molecular evolution has occurred.C) House cats and African wild cats are both members of the family Felidae.D) Divergent morphological evolution has occurred.E) House cats and African wild cats share a recent common ancestor.

Sequencing DNA from different organisms has been a breakthrough for phylogenetics because: A) we can now build heat-tolerant animals. B) we now have a method to determine the relatedness of organisms that leave no fossils. C) it has reduced the impact of antibiotic resistance in bacteria. D) we can now recreate genomes from the past. E) All of the above are correct.